DETECTION OF ANTI-ENDOTHELIAL CELL ANTIBODIES IN PATIENTS AFTER HEART TRANSPLANTATION AND THEIR RELATION TO ENDOTHELIAL CELL ACTIVATION.

Abstract

A284 Aims: Transplant-associated coronary artery disease is the most serious long-term complication after cardiac transplantation (TxCAD). Although often associated with chronic production of anti-endothelial cell antibodies (AECA), the precise role of antibodies in chronic rejection remains uncertain. In the present study we have screened serum of patient after heart transplantation for the presence of AECA and discussed their activation potential on endothelial cells. Methods: Up to 6 years after transplantation, 175 sequential sera were retrospectively collected from 37 patients. Serum antibody activity was measured using a cellular enzyme-linked immunosorbent assay (ELISA) in which human endothelial cells (EaHy926) were used as target cells. The effect of antibodies on human saphenous vein endothelial cells (HSVEC) and adhesion molecule expression was measured by cellular ELISA. Results Long-term transplantation time resulted in a significant increase in the antibody activity (1-2 years: 33 % vs 60 % for IgA; 3-6 years: 13 vs 40 % for IgM). There was no correlation between AECA and the number of acute rejection episodes. Only two patients showed increased levels of AECA (IgG-type) without any signs of TxCAD. In the early postoperative phase (up to 3 months) serum concentrations of interleukin-6 and tumor necrosis factor-soluble receptor I were elevated and correlated with the amount of IgG. Even 3 years after transplantation the level of IgG-AECA remained elevated in one patient (factor 3 level above probands). Incubation of HSVEC with 30 % of the serum for 48 h resulted in an increase of the proliferation activity (20-40 %). The basal expression of adhesion molecules was not influenced, whereas the tumor necrosis factor alpha induced expression of E-selectin increased by a factor of 1.8. To exclude the influence of soluble factors in serum (medication) it will be necessary to purify the antibodies. Conclusions: The presence of AECA in the serum of patients after transplantation may be a prognostic marker for endothelial injury. It remains to be seen whether antibodies of IgA and IgM-type cause cell activation.